The present invention relates to heating devices, and more particularly pertains to oven units for heat treating sealant strip material applied to the perimeter edges of window units, either single-, double-, or triple-pane window units, by utilizing emitters which generate and direct radiant heat energy upon the sealant strip material.
A critical step in the production of window units is the heat treating of sealant strip material that is applied to the perimeter edges of the window unit. As double- and triple-pane windows predominate the marketplace, the sealant strip material, the most common kind being polyisobutylene, also known as butyl hot melt, or a swiggle strip material, is utilized as an adhesive for securing each window pane in spaced, parallel relationship to one another and also for providing a thermal and moisture insulative barrier between the sash and the panes of glass. The hermetic seal achieved by the sealant strip material prevents moisture seepage from the exterior atmosphere through the frame and the metal spacers, located on the inside perimeter of the window panes, into the enclosed region within the window panes, thus preventing fogging of the interior of the window unit through condensation. In addition, the hermetic adhesion of the sealant strip material to the perimeter edges of the window unit prevents conductive heat loss from the interior of the dwelling through the window unit to the external environment. The process of heat treating and curing the sealant strip material plays a critical role in the production of multi-pane window units that have a high R value and a low E (emissivity) value.
The prior art discloses a number of devices for curing an adhesive material applied to the perimeter edges of a workpiece. For example, the Hutter, III patent, U.S. Pat. No. 4,391,663, discloses a plurality of upright electrical-powered radiation heaters for generating radiation heat energy. The workpiece to be treated is a plurality of window or door units stacked vertically upright in a movable cart. The cart is placed close to the radiation heaters so that the adhesive substance placed along the perimeter edge of each door or window unit receives the radiation heat energy generated by the heater. The heaters themselves are positioned on two of the four sides of the door or window unit.
The Crain, et al. patent, U.S. Pat. No. 4,406,944, discloses an infrared furnace including a pair of opposed sidewalls which have a plurality of aligned ceramic holders located thereon. In addition, a plurality of spaced-apart quartz tubes extend longitudinally through the infrared furnace and support an endless conveyor belt thereon.
The McGinty patent, U.S. Pat. No. 4,540,876, discloses a rectangular chamber for heat treating electronic components and integrated circuits. The furnace includes six plain reflecting walls and two sets of heat radiation lamps, the second set of heat radiation lamps spaced apart from and parallel to the first set of heat radiation lamps.
The Brumm, et al. patent, U.S. Pat. No. 4,820,365, discloses a method and apparatus for a glass edge sealant curing system. The apparatus includes a conveyor for conveying a stack of window units coated with an edge sealant material and a heater assembly with infrared heating units placed back-to-back at a midpoint on the conveyor.
Despite the ingenuity of the foregoing devices, there remains a need for an oven unit which utilizes radiant heat energy generating emitters having a rapid response time for generating maximum heat energy and an equally rapid response time for cooling down. In addition, there is a need for an oven unit wherein the emitters are quickly and easily insertable and removable as well as vertically adjustable to accommodate different thicknesses of window units. Furthermore, there remains a need for an oven unit which utilizes a maximum amount of reflected radiant heat energy for heat treating the sealant material applied to the window unit being conveyed therethrough.